Fuel injectors supply the combustion chamber of an engine with fuel. These injectors flow fuel past a check member and through nozzle orifices. An injector is designed to atomize and disperse fuel as evenly as possible throughout the combustion chamber for a complete and thorough combustion of that fuel. A properly functioning fuel injector flows fuel through its nozzle orifices and sprays a finely atomized mist of fuel into the combustion chamber.
When this fuel flow becomes turbulent, cavitation can occur. Cavitation causes both a reduced effective flow rate, as well as a less even atomization. Diminished atomization can result in incomplete combustion, which increases emissions and lowers fuel efficiency. Turbulent, cavitated flow in the injector's nozzle orifices is detrimental to both fuel injector and engine performance.
One attempt to address this issue is described in U.S. Pat. No. 6,007,000 issued to DeLuca on Dec. 28, 1999. The '000 patent describes a fuel injector nozzle with a hemispherical sac shape, a reduced sac volume, and a center of volume of the sac region that is below a center of radius of the sac bottom. By modifying the sac design in this way, the '000 patent attempts to create a less turbulent flow at the entrances of the nozzle orifices in the sac. The '000 patent claims that this less turbulent flow improves the distribution of fuel throughout the combustion chamber, and results in a more complete combustion of the fuel.
Although the nozzle design of the '000 patent may reduce some of the turbulence in the injector fuel flow, the design may not reduce turbulence enough. The prior art nozzle design's use of a hemispherical sac design creates a sharper transition into the nozzle orifice. This sharper transition may result in undesirable cavitation in the nozzle orifice. Furthermore, the '000 patent may leave a sac volume larger than is necessary.
The present disclosure is directed toward one or more of the problems set forth above.